/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.streampark.flink.connector.doris.util;

import java.io.StringWriter;

public class DorisDelimiterParser {

  private static final String HEX_STRING = "0123456789ABCDEF";

  public static String parse(String sp) throws RuntimeException {
    if (sp == null || sp.isBlank()) {
      throw new RuntimeException("Delimiter can't be empty");
    }
    if (!sp.toUpperCase().startsWith("\\X")) {
      return sp;
    }
    String hexStr = sp.substring(2);
    // check hex str
    if (hexStr.isEmpty()) {
      throw new RuntimeException("Failed to parse delimiter: `Hex str is empty`");
    }
    if (hexStr.length() % 2 != 0) {
      throw new RuntimeException("Failed to parse delimiter: `Hex str length error`");
    }
    for (char hexChar : hexStr.toUpperCase().toCharArray()) {
      if (HEX_STRING.indexOf(hexChar) == -1) {
        throw new RuntimeException("Failed to parse delimiter: `Hex str format error`");
      }
    }
    // transform to separator
    StringWriter writer = new StringWriter();
    for (byte b : hexStrToBytes(hexStr)) {
      writer.append((char) b);
    }
    return writer.toString();
  }

  private static byte[] hexStrToBytes(String hexStr) {
    String upperHexStr = hexStr.toUpperCase();
    int length = upperHexStr.length() / 2;
    char[] hexChars = upperHexStr.toCharArray();
    byte[] bytes = new byte[length];
    for (int i = 0; i < length; i++) {
      int pos = i * 2;
      bytes[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
    }
    return bytes;
  }

  private static byte charToByte(char c) {
    return (byte) HEX_STRING.indexOf(c);
  }
}
